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2.3 Stereo Image Workstation (PI-1000) 
The PI-1000 is an apparatus which conducts 3D digital-data measurement and plotting, employing the image 
information obtained through a high-resolution CCD camera (PC-1000) and an image scanner (PS-1000) made from 
our company. This apparatus, in fact, has a wide range of applicability in 3D measurement, such as civil 
engineering measurement or industrial measurement. 
The 3D measurement by means of the PI-1000 is conducted as follows: 
First, the image data obtained by the high-resolution CCD camera (PC-1000), etc., is read into the memory from 
optical disks, and exterior orientation procedures are conducted. Then, based on the parameters obtained by the 
exterior orientation, the image is automatically corrected and the stereo model is rectified. 
Next, the rectified images of the right and left side are displayed on a 3D image display and superimposed on 
floating marks (Ohtani,Ishii, 1992). 
There are two measurement modes: one is manual that measures interactively and the other is an automatic DTM. 
The former is conducted by employing polarized glasses, by performing stereoscopic observation on the 3D image 
display, by controlling the floating marks by means of a 3D mouse, and by executing 3D measurements for each of 
the points. The latter is a mode wherein a computer makes batch measurements by placing evenly spaced grid 
points on the left image and by performing image correlation processing. Thus, the 3D coordinates of the grid 
points are determined. 
3. CALIBRATION EXPERIMENTS OF THE HIGH-RESOLUTION CCD CAMERA 
3.1 Camera Calibration 
"Self-calibrating bundle adjustment" was applied for calibration of the CCD camera. For correction model, the 
following equations (1) and (2) were employed. 
  
Ax 2 —xo * x'(kyr? 9 kar*) - py(r? - 2x2) - 2pox/y/ (1) 
Ay 2 -yo t Yr? € kar*) * 2pyx!y! e py(r? € 2y?) (2) 
x! 2 x-Xo, Y! »y- yo, r! 2 x^ « y? 
x,y image coordinates — xo, yo :coordinates of principal point 
ki, k» :parameters for radial lens distortion 
  
P1,P2 :parameters for tangential lens distortion . © ue 
For the collinearity condition, the following equations (3) Fig.6 3D test-field 
and (4) were employed. 
  
au (X- Xo) * A12(Y— Fo) + A13(Z— Zo) : 
=n Ax. (3 
x A To Yo) * as3(Z — Zo) * ( ) 
  
  
a31(X — Xo) * axz(Y — Yo) - a33(Z — Zo) 
  
f:principal distance a; ‘rotation matrix 
X.Y, Z coordinates of object points 
  
X»o, Yo, Zo coordinates of projection centre 
  
3.2 Experiment 
In the experiment, a 3D test-field (Fig.6) was taken at a 
distance of 1000mm and at a principal distance of 
36.928mm from the CCD camera from 7 different directions 
or positions, in such a way that the images could be 
overlapped 100%, as illustrated in Fig. 7. The dimensions 
of the 3D test-field were approximately 500mm in both height and width, and 30,70,110, and 150mm in 4 stages of 
depth. The 16 control points were arranged, topped with LEDs of 4mm in diameter for automatic position detection. 
The 3D coordinates of this 3D test-field were measured at the accuracy of =3 4m, by means of a contact-type 3D 
measurement apparatus. 
Fig.7 Configuration of image acquisition 
  
  
  
IAPRS, Vol. 30, Part 5W1, ISPRS Intercommission Workshop “From Pixels to Sequences”, Zurich, March 22-24 1995